It is definately Olympus (MTB) c'91. -The same as Centaur, but with the black body and steel cage. -It should have 'Campagnolo' engraved on the cage..?
This sold for about £45 in '91, so was dearer than XT, but didn't work as well as the big Ss' back then, so it's hard to compare. It was MUCH sturdier though (and heavier).